1. Field of the Invention
The present invention relates to transport systems, and more particularly, to passive wire detection techniques.
2. Background
One of the leading causes of catastrophic in-flight helicopter and tilt-rotor aircraft (or any other transportation system, used interchangeably throughout this specification) accidents is due to contact with static objects, for example, contact with wires (“wire-strike”). Such accidents typically occur when a helicopter collides with power lines, wires or communications lines. Many of these accidents result in fatalities, and they are especially a problem during low altitude helicopter cruising and maneuvering.
Wires are oftentimes difficult to see by naked eye due to their small size, and this can be exasperated even further by bad weather and visual clutter. FIG. 1A illustrates helicopter 10 flying towards wires 20 (power lines). If the pilot does not detect the power lines on time, then helicopter 10 can crash resulting in fatalities and loss of property.
Active wire sensors in helicopters could be used to mitigate this problem. An active sensor is a detection device that requires input energy from a source other than the target, which is being sensed. An example of an active sensor is a measuring instrument that generates a signal, transmits it to a target, and receives a reflected signal from the target. Information concerning the target is obtained by comparison of the received signal with the transmitted signal. Active sensors cannot be used in cases where stealth/secrecy is required, for example, military operations, and hence this is not a desirable solution for these applications.
Another potential solution is to use passive sensors. Passive sensor devices detect without emitting any energy signals that can cause them to be detected. The detection occurs as a result of radiation from the target or reflection of ambient energy on the target.
However, even with high resolution passive sensors, wires can be very difficult to see at minimum avoidance ranges because they are often sub-pixel, embedded in wire-like clutter, and/or have poor signal-to-noise ratio (“SNR”).
Another option is to use real-time image processing to detect the wires. However, conventional real time processing techniques rely on a host of convolution and filtering techniques. Low latency requirements coupled with standard real time processing constraints place severe limits on the size of the convolution kernels and filter sizes. This in turn, degrades wire detection performance and reliability.
Therefore, there is a need for a method and system for parallel real-time passive wire detection techniques, which can efficiently detect wires and notify the pilot of wires to minimize the risk of wire prone accidents.